The functional requirements of the Android Application are defined below. 

The system must:
\begin{enumerate}
  \item Be able to recognise a user.
  \item Be able to register new users.
  \item Allow the users to change their own information. 
  \item Have authentication data like nick and password for a user.
  \item Not allow two or more users with the same nick.
  \item Have a process to identify users.
  \item Be able to store information like name, surname, email, phone, country and address.
  \item Be able to display a world map and the interface to navigate it.
  \item Allow users to search for other users by nick, name, surname and/or country.
  \item Allow a user to make a friend request.
  \item Allow the user to see friend requests he has.
  \item Allow the user to accept or reject friend requests.
  \item Be able to detect location changes of a logged in user.
  \item Be able to send periodically the GPS position in order to update the user's location.
  \item Allow the user to see his friends, if they have already a position associated.
  \item Be able to draw the user's friends in a map using their last known position.
  \item Allow the user to create new notes.
  \item Allow the notes to have a text and/or a photo.
  \item Allow the user to see a friend's comments.
  \item Display the comments in a map using the location of the comment.
\end{enumerate}